The long-term goal of the proposed research is to develop a novel quantitative particle agglutination technology for improving the performance of blood typing assays. The conventional hemagglutination blood typing assays have serious drawbacks such as limited sensitivity, long time of incubation, subjectivity and large amount of reagents. It is in this context that we propose to develop a new technology, which is free from the aforementioned limitations of the conventional hemagglutination assays. The proposed immunoassay is a sensitive and rapid method that utilizes inexpensive instrumentation. The Specific Aims of Phase II are: 1) To further explore all variables affecting the performance of the new blood typing detection assays and optimize the performance of the assay; 2) To design and assemble an ?rototype of the device for performing of several blood typing assays simultaneously. The ?rototype is intended to test the design of every technical element of the system before it is implemented in the final pre- production prototype; 3) To validate the detection assays for determination of blood groups (including weak D group and C, c, E, e and K antigens) and expected antibodies (reverse typing); To examine a statistically significant number of clinical samples for each assay, and carry out statistical analysis and demonstrate reproducibility of the obtained results; To compare performance of the conventional and newly developed assays. Significantly, the new method presents a general approach for enhancement and detection of agglutination of particles of different origin, including latex, silic microparticles, and biological cells.